For a candidate who has made his own business background exhibit A in the argument that he could run the US economy better than his opponent, Mitt Romney has a case to answer over his involvement with Bain Capital. He plainly did not "leave" the private equity firm in 1999, if a series of filings to the Securities and Exchange Commission show him listed as the sole shareholder, sole director, CEO and president two years later. Instead of denying he had anything to do with the firm that helped other companies outsource jobs overseas, lay off steel workers and wipe out their pensions, Mr Romney could lay the matter to rest by publishing his tax returns and the minutes of Bain Capital meetings for that period.

But none of that means it is particularly clever for Barack Obama to keep on attacking Mr Romney over his asset-stripping days. It's fine for his electoral base, but what about the independents he also needs to swing behind him? What these American voters will want to know in November is what Mr Obama has done to turn the jobs figures around. Four days before they vote in November, the monthly jobs report from the labour department will tell them what they already know in July – that unemployment is wedged in place at above 8%. That figure in itself understates those in part-time working or who have stopped looking for work. Of course, mud sticks, as Ed Gillespie, one of Romney's advisers, was the first to admit. But the high-minded president, who in 2008 pledged to rise above the partisan fray, should be careful too about how much mud he throws.

David Axelrod, the strategist for the president's re-election, is right to remind us four years on that when Mr Obama took office, America was losing jobs at the rate of 800,000 a month and it takes years to turn the supertanker around. He is also right that the Republican remedy – tax cuts skewed to the wealthy, the cutting of federal government programmes, the return to casino capitalism – would lock the rudder in place. If anything, the jobs market is where it is because Mr Obama was too timid in the stimulus he applied after the banking crash. But all that is history. In November it's his record, not Mr Romney's, that they will be voting on.